Plasterboard, also known as drywall, gypsum board or wallboard, is a panel made of gypsum plaster pressed between two thick sheets of paper. Plasterboard panels are typically mounted on structural members to make interior walls and ceilings of buildings. It is sometimes necessary, particularly when a building is erected, to cut openings in plasterboard to provide access to electrical switch and outlet boxes mounted on the structural members. An opening may be cut before the plasterboard is mounted on the structural members, or it may be necessary to cut the opening while the plasterboard is in situ mounted on the structural members.
The usual process of cutting openings comprises firstly marking on the plasterboard where the opening is to be cut. Then, a workman cuts the opening using a saw. The opening typically has rough edges. This process is time consuming, typically taking a practiced workman 15 to 30 minutes. The process is also error prone and typically makes a mess. Also, the saw can extend beyond the plasterboard to make contact with an object on the far side of the plasterboard from the workman. This can cause damage to the object. Since there may be electrical wiring, this also presents danger to the workman.
A known document, U.S. Pat. No. 3,503,294, describes a sawing apparatus. This sawing apparatus includes a crank member that is coupled to a rotational power source. Sawing action of four blades is driven by eccentric movement of the crank member. The sawing apparatus is unstable in use, which may lead to a user applying different blades to an object to be cut at different pressures. This may disadvantageously lead to the object being cut more quickly in some regions than in others. In addition, the eccentric motion of the crank causes vibration of the device. The issues of instability and vibration make the apparatus difficult and unpleasant to use, and may lead to unsatisfactory and inaccurate cutting.
It is an object of the present invention to address these issues.